in the present paper, the deformation zone of the ecae (equal channel angular extrusion) process was investigated using the upper bound theorem. for this purpose, the shape of the streamlines in the deformation zone was assumed to be cubic bezier curves. then, the force required for the ecae process was optimized with regard to the parameters defining the shape of streamlines by the upper bound...

In order to get an optimal use of all the interesting features for free-form mod-eling provided by sophisticated geometric models (Bezier, B-Spline, NURBS), we propose a deformation technique based on the concept of normalized operators. Such an operator can be viewed as a black-box which encloses | and hides to the user | the high number and the complexity of the parameters involved during a d...

The hot deformation behavior and microstructural evolution of Ti-44Al-5V-1Cr alloy were investigated by hot compression tests at temperatures of 1000–1250 ◦C and strain rates of 0.001–1 s−1. It was indicated that the dependence of peak stress on deformation temperature and strain rate could be accurately described by a hyperbolic sine type equation. The activation energy, Q, was estimated to be...

Plastic deformation of ARMCO iron processed by ECAP up to a maximum equivalent strain of sixteen (i.e., 1, 4, 8, and 16 ECAP passes) following route Bc was investigated by analyzing its microstructure and the stress-strain curves obtained after tensile tests at different levels of deformation. Three values of deformation (two in the plastic region taking into account the modified Crussard-Jaoul...

the current study conducted a finite element (fe) and experimental investigation on tubular channel angular pressing as a noble severe plastic deformation technique for producing ultrafine grained and nanostructure tubular components. to examine the effects of the tcap process on the strain distribution and deformation behavior, fe simulations were employed. the fe results demonstrated that equ...

determination of critical points on hot stress-strain curve of metals is crucial in thermo-mechanical processes design. in this investigation a mathematical modeling is given to illustrate the behavior of metal during hot deformation processes such as hot rolling. the critical strain for the onset of dynamic recrystallization has been obtained as a function of strain at the maximum stress. in a...

Till now, different constitutive models have been applied to model the hot deformation flow curves of different materials. In this research, the hot deformation flow stress of API X65 pipeline steel was modeled using the power law equation with strain dependent constants. The results was compared with the results of the other previously examined constitutive equations including the Arrhenius eq...

dynamic recrystallization, drx, behaviour of a precipitation hardened, ph, stainless steel was studied in connection with microstructural developments in a compression test. the experimental results showed that the dominant mechanism of softening is drx, but at high strain rates and low temperatures, ie, high zener-holman parameter, z, work hardening and dynamic recovery, drv, produced a pancke...